Values and Expressions

Values

In programming, we regularly deal with values. These so-called values are just the "things" that we can access inside of our programs. For example, a number would be considered a value. A piece of text "Hello world!" would also be considered a value.

It wouldn't make much sense to do arithmetic (like adding or subtracting) without numbers. In a similar way, it wouldn't make much sense to program without values. These values hold the information that we want to work with. Let's look at an example.

$text("Hello world!", 25, 30);

In this example, we've got a handful of values!

• "Hello world!" is a value. We generally call text values like this string values, because they are "strings" of characters. (Think words and sentences.)
• 25 and 30 are both values that you should recognize. They're just numbers.
• $text is technically a value too! But it's a function, and we'll talk more about those in a later chapter.

Values themselves are incredibly useful to us, but not all that interesting by themselves. However, they become quite a bit more interesting once we start combining them!

Expressions

Values are very plain and they don't ever change. For example, 5 is always 5 🤷‍♂️. However, once we start putting values together, things start to get a little more interesting! For example, adding numbers is a bit more useful than just looking at the number 5!

In programming, we combine values together to create expressions. Here are some examples of expressions:

• 5 + 3
• (3 + 9) / 4
• "Hello " + "world!"

Expressions are just combinations of values that evaluate to a value. This is important: every expression can be evaluated to a single value. Let's revisit our previous expressions in a code editor.

$log(5 + 3);
$log((3 + 9) / 4);
$log("Hello " + "world!");

Notice that, in the our log, each of our expressions evaluates to a single value!

• 5 + 3 has a value of 8.
• (3 + 9) / 4 has a value of 3.
• "Hello " + "world!" has a value of "Hello world!".

Operators

In the expression 5 + 3 we combined two values (5 and 3) to create a different value (8). In this case, we used addition to combine these two values. We call addition an operator.

Operators are tools for taking one or two values and turning them into a new value! You're likely familiar with some math-related operators, such as addition, subtraction, and multiplication. But there are plenty of operators for working on different types of values, like strings (or words) and lists.

Operators are an important part of creating expressions, and we'll be using them regularly throughout this book! So let's take a look at one last example. Try to identify all of the operators you see (things that take one or two values and return a new one). Don't worry if you don't know what they all do.

$log(72 * 15);
$log(8 % 3);
$log(-32);